Studies of the effects of drugs on the behavior of individual animals in isolated environments have provided considerable information about psychoactive drugs. However, there is presently little information about the effects of drugs on individuals living in social groups. The objective of this research is to characterize the effects of selected drugs on readily identifiable behaviors exhibited by members of social groups of nonhuman primates. The proposed experiments will be concerned with the effects of acute administration of a range of doses of a variety of behaviorally active drugs (morphine, cocaine, d-amphetamine, pentobarbital, chloral hydrate, diazepam, delta 9-tetrahydrocannabinol, secobarbital, naloxone and naltrexone) on the social behavior of group-living Macaca arctoides. Specifically, experiments will be conducted to determine the effects of the administration of drugs to individual adult males and to adult females with young. The studies will determine the range of doses having effects on behaviors of monkeys in social groups, determine whether drug effects are related to dominance rank, and describe the effects on the maternal behavior of mothers with young. The behavior of social, group-living nonhuman primates can contribute to our understanding of the effects of drugs on human and animal behavior, and determine the generality of the effects observed in individual animal experiments. We believe that it is within the dynamic network of social relationship characteristic of primate societies that the behavioral effect of drugs might be evaluated.